Quite logical. A circuit can be switched to (negative) ground.
The switch doesn't have to be in the positive lead - it just normally is...
Hartley18, I've been doing electrical and electronics for longer than most boats and/or their owners on this forum have been alive. I kind of rather know that
My point, which you appear to be studiously ignoring, is that it would be illogical to switch the half of the energy source that's connected to "common" or "ground" in an electrical system, not-to-mention quite possibly dangerous.
Have you ever actually seen anything, car, boat, whatever, purposely wired that way, by somebody who knew what they were doing?
The only reason people put a switch in the positive lead is to isolate power from the entire circuit when it's switched off - for safety - no other reason at all.
So... switches on the positive side of an energy source aren't used to remove power from the loads in order to turn them off?
Why would your rigging be part of the electrical ground? I don't think it should be, mine isn't, and I don't think I have seen one that is.
Every last bit of metallic hardware I've seen on Abracadabra, save the stanchions, bow pulpit and stern pulpit, are bonded together. That includes all the chainplates. The shrouds and stays are metallic, and they're fastened to the "grounded" chainplates. Thus Abracadabra's rigging is "grounded." This is not uncommon at all.
... some voltage will generally exist between the rigging and battery positive. Exactly how much will depend on the construction of the boat.
I presume you're talking about a boat with most metallic bits bonded to common "ground" and a positive ground system? True, but it should be relatively negligible. Otherwise that would tend to indicate poor connections/bonding between metallic bits.